Name:	extr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedInPeriodAggregateFairMarketValue
Namespace Prefix:	extr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Share based compensation arrangement by share based payment award equity instruments other than options released in period.

No definition available.

Name:	extr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReleasedInPeriod
Namespace Prefix:	extr_
Data Type:	xbrli:sharesItemType
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Period Type:	duration

Share based compensation arrangement by share based payment award equity instruments other than options released in period weighted average grant date fair value.

No definition available.

Name:	extr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsReleasedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	extr_
Data Type:	dtr-types:perShareItemType
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Share based compensation arrangement by share based payment award equity instruments other than options vested and expected to vest outstanding aggregate fair market value.

No definition available.

Name:	extr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingAggregateFairMarketValue
Namespace Prefix:	extr_
Data Type:	xbrli:monetaryItemType
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Share based compensation arrangement by share based payment award equity instruments other than options vested and expected to vest outstanding number.

No definition available.

Name:	extr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingNumber
Namespace Prefix:	extr_
Data Type:	xbrli:sharesItemType
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Share based compensation arrangement by share based payment award equity instruments other than options vested and expected to vest outstanding weighted average grant date fair value.

No definition available.

Name:	extr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndExpectedToVestOutstandingWeightedAverageGrantDateFairValue
Namespace Prefix:	extr_
Data Type:	dtr-types:perShareItemType
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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Data Type:	xbrli:sharesItemType
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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValueRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.